Document DE 103 42 389 A1 discloses hydraulic control equipment for a transmission, having a total of four actuating cylinders (actuator cylinder units or hydraulic cylinder units), having a cylinder housing (main unit with respective cylinder chambers) and actuating pistons (pistons), which are guided therein to be longitudinally displaceable along cylinder axes and which can each be acted on hydraulically and are operatively connected with one of the setting elements (selector rods with selector forks) of the transmission. The actuating cylinders are already combined in assembly-friendly manner into a subassembly which can be flange-mounted by way of a flange surface on a casing of the transmission.
In the document DE 103 42 389 A1 there is in addition general discussion that the displacing movements produced by the hydraulic control device can be carried out in travel-sensed or travel-controlled manner if this is desired for reasons of control and/or safety. However, details with respect thereto are not disclosed in this document.
For determination of the gear setting, a position transmitter, for example a magnet, is usually provided at the selector fork or, as described in, for example, document DE 10 2007 062 353 A1, at the selector rod and co-operates with a position sensor suitably arranged to be fixed relative to the transmission casing. In the case of, for example, four selector rods as shown in the prior art mentioned in the introduction the outlay connected with the assembly and contact-making of such a sensor system is certainly not inappreciable.
Moreover, an integrated control module, which comprises a plurality of hydraulically loadable actuating pistons operatively connected with selector forks so as to selectably displace these, for a twin-clutch transmission is known from the document US 2011/0203361 A1 (FIGS. 4 and 5). In that case, two cylinder housings are associated with each actuating piston, in particular, a cylinder housing for each actuating direction, with a “free”, i.e. externally accessible, annular groove at the actuating piston therebetween, for connection with the selector fork, wherein in addition each cylinder housing receives at least two different actuating pistons.
More precisely, the arrangement is such that, of the total of four actuating pistons, in each instance two actuating pistons coaxially seated one behind the other form a piston pair and the two piston pairs formed in this way are arranged parallel to one another, wherein a total of three cylinder housings is provided, in particular two outer cylinder housings each with two cylinder bores and a central cylinder housing, which is disposed therebetween, with four cylinder bores. However, the thus-produced spatial proximity and alignment of the actuating pistons with respect to one another has the consequence that mechanical transmission elements of complicated design have to be provided in order to transmit the piston movements to the selector forks.
Furthermore, the center cylinder housing in this prior art is provided with a total of four sensors which are each associated with a respective actuating piston for detection of the piston movements. In that regard, each actuating piston carries a signal element which co-operates with the respectively associated sensor. The electrical lines to and from the sensors are brought together on the center cylinder housing in cruciform shape to form a main section which ends with a connecting block at the center cylinder housing. By way of the connecting block there is an electrical connection to an electronic transmission control subassembly which is arranged directly adjacent with respect to the center cylinder housing and is integrated in the control module. Finally, two rotational speed sensors are also mounted on the transmission control subassembly and serve the purpose of detecting the rotational speed of two transmission input shafts during operation.
Due to the spatial proximity of the center cylinder housing with respect to the transmission control subassembly, the integration thereof in the control module and the integration of the complete stroke sensor system in the center cylinder housing the above-mentioned contact-making problem at the time of assembly does not, however, arise with this prior art.
What is desired is a hydraulic or pneumatic actuating device for actuation of setting elements in a motor vehicle transmission, which is provided with a sensor system which requires only a smallest possible amount of effort for assembly and contact-making.